The Chicago area is in the midst of its longest rain-free period since early June. Tuesday marks the 10th rain-free day to occur here after the area’s third-wettest August and an April through August growing season which was the 31st wettest of the past 137 years. Changes to the current dry pattern loom later this week–but Wednesday should remain dry as well. A strong northward surge in low-level moisture brings increasingly muggy air into the area–a development expected to double the amount of moisture in the air here by Thursday. Almost 2″ of water is to be suspended in the humid late-week air mass as it begins to tangle with the season’s strongest southward push of cool air to date. The chill won’t reach Chicago until Sunday, but the cool push produces a southward buckle or trough in the jet stream beginning later this week. This is a thunderstorm-provoking upper-air orientation. Several waves of rain could bring 1-2″ or more to the area before chilly air crashes into Chicago on blustery northerly winds by Sunday afternoon.
Sources: Frank Wachowski, NWS co-op observers, WeatherBug, NOAA-NCEP date
WGN-TV/Monika Bec and Patrick Korellis
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN-TV News at noon and 9 p.m.
WGN-TV meteorologists Steve Kahn, Richard Koeneman and Paul Dailey plus weather producer Bill Snyder contribute to this page.
